1. Field of the Invention
The invention relates to exterior lighting fixtures. More particularly, the invention relates to a visor which is retrofittable to an existing PAR bulb to thereby reduce glare, increase lighting efficiency, control light output, and minimize light trespass and light pollution.
2. State of the Art
For many years astronomers complained that the nighttime light from large cities interfered with their ability to detect far off faint stars. It is for this reason that most astronomical observatories are located far away from densely populated cities.
More recently, other groups have concerned themselves with the adverse effects of uncontrolled exterior lighting. These groups include the New England Light Pollution Advisory Group (NELPAG), the International Dark-Sky Association (IDA), the Illuminating Engineering Society of North America (IESNA), the Commission Internationale de l""Eclairage (CIE), the Electric Power Research Institute (EPRI), and the UK Institution of Lighting Engineers, (ILE).
The adverse effects of uncontrolled exterior lighting include xe2x80x9clight trespassxe2x80x9d, light that strays from its intended purpose and becomes an annoyance or nuisance, and xe2x80x9clight pollutionxe2x80x9d, night-sky brightness (sky glow) caused by light illuminating particulate matter in the atmosphere. The sources of light pollution and light trespass typically include light projected above a horizontal plane or light reflected from illuminated surfaces such as roadways.
An increasing number of states and municipalities have been involved in the alteration of the use of exterior lighting by instituting laws and ordinances. One solution has been the establishment of a xe2x80x9clighting curfewxe2x80x9d, an established time frame within which lighting must be maintained according to predetermined levels. Other solutions include restrictions on the type of exterior lighting fixtures which may be used.
One of the most common exterior lighting fixtures is the simple PAR bulb flood (or spot) light 10 which is illustrated in prior art FIG. 1. The fixture 10 includes a mounting plate 12, a weather resistant bulb socket 14 and a replaceable PAR bulb 16. The familiar PAR bulb 16 has a frustroconical portion terminating in a lip 18. These fixtures 10 may not pose a serious problem if the axis of the bulb is aimed thirty or forty degrees below horizontal. They are almost always a problem when aimed above horizontal as shown in FIG. 1. These fixtures are often used to illuminate signs, buildings, monuments, and the like and are either aimed up from the ground as illustrated, or mounted on the side of a building. When so used, these ubiquitous fixtures contribute substantially to light trespass and light pollution.
Prior art FIGS. 2-4 illustrate products available from RAB Electric Manufacturing, Inc., 170 Ludlow Avenue, Northvale, N.J. 07647. These fixtures are often referred to as xe2x80x9cdark skyxe2x80x9d or xe2x80x9cfriendlyxe2x80x9d lighting fixtures. The fixtures 20 and 30 shown in prior art FIGS. 2 and 3, respectively, include a die cast aluminum housing 22, 32, respectively, which covers the sides of a standard PAR bulb 16 and extends approximately one inch beyond the bulb to provide a shade to reduce glare. An optional visor 40 shown in prior art FIG. 4 is provided with an engaging end 42 so that it securely mates with either fixture 20 or 30.
The fixtures shown in prior art FIGS. 2-4 are highly effective in controlling light pollution and light trespass. However, they have three significant disadvantages. First, they are expensive compared to the common fixtures shown in prior art FIG. 1. Second, in order to obtain their benefits, existing fixtures must be replaced, which includes re-wiring by a licensed electrician. Third, unless they are properly dimensioned, it is difficult to install and remove bulbs in these fixtures. Those skilled in the art will appreciate that the space between the circumference of the bulb 16 and the hood 22, 32 is often too small to allow thumb and fingers to grip the bulb during installation/removal. Thus, a special tool is often required for this purpose.
It is therefore an object of the invention to provide a dark sky/friendly lighting fixture which overcomes the disadvantages of the prior art.
It is also an object of the invention to provide a dark sky/friendly lighting fixture which is relatively inexpensive.
It is another object of the invention to provide a dark sky/friendly lighting fixture which does not require the replacement of existing fixtures.
It is still another object of the invention to provide a dark sky/friendly lighting fixture which does not inhibit the installation or removal of bulbs.
In accord with these objects which will be discussed in detail below, the PAR bulb visor of the present invention includes an accessory visor with a plurality of spaced apart spring clips which is adapted to removably attach to the lip of a PAR bulb. The visor of the present invention is retrofittable to virtually any existing PAR bulb fixture where the lip of the bulb is exposed. The visor of the invention is inexpensive to manufacture. It does not require casting and can be made from inexpensive sheet metal. Since the visor of the invention can be easily installed and removed from the lip of an existing PAR bulb, it does not interfere with the installation/replacement of the bulb.